Shear strain and inflammation‐induced fixed charge density loss in the knee joint cartilage following ACL injury and reconstruction: A computational study

Inflammation is a variable feature of osteoarthritis (OA), associated with joint symptoms and progression of disease. Signs of inflammation can be observed in joint fluids and tissues from patients with joint injuries at risk for development of post-traumatic osteoarthritis (PTOA). Furthermore, inflammatory mechanisms are hypothesized to contribute to the risk of OA development and progression after injury. Animal models of PTOA have been instrumental in understanding factors and mechanisms involved in chronic progressive cartilage degradation observed after a predisposing injury. Specific aspects of inflammation observed in humans, including cytokine and chemokine production, synovial reaction, cellular infiltration and inflammatory pathway activation, are also observed in models of PTOA. Many of these models are now being utilized to understand the impact of post-injury inflammatory response on PTOA development and progression, including risk of progressive cartilage degeneration and development of chronic symptoms post-injury. As evidenced from these models, a vigorous inflammatory response occurs very early after joint injury but is then sustained at a lower level at the later phases. This early inflammatory response contributes to the development of PTOA features including cartilage erosion and is potentially modifiable, but specific mediators may also play a role in tissue repair. Although the optimal approach and timing of anti-inflammatory interventions after joint injury are yet to be determined, this body of work should provide hope for the future of disease modification tin PTOA.

Anterior cruciate ligament reconstruction is widely accepted as the treatment of choice for individuals with functional instability due to anterior cruciate deficiency. There remains little information on the epidemiology of anterior cruciate ligament reconstruction with regard to adverse outcomes such as hospital readmission and subsequent knee surgery. We sought to identify the frequency of anterior cruciate ligament reconstruction, the rates of subsequent operations and readmissions, and potential predictors of these outcomes. The Statewide Planning and Research Cooperative System (SPARCS) database, a census of all hospital admissions and ambulatory surgery in New York State, was used to identify anterior cruciate ligament reconstructions performed between 1997 and 2006. Patients with concomitant pathological conditions of the knee were included. The patients were tracked for hospital readmission within ninety days after the surgery and for subsequent surgery on either knee within one year. The risks of these outcomes were modeled with use of age, sex, comorbidity, hospital and surgeon volume, and inpatient or outpatient surgery as potential risk factors. We identified 70,547 anterior cruciate ligament reconstructions, with an increase from 6178 in 1997 to 7507 in 2006. Readmission within ninety days after the surgery was infrequent (a 2.3% rate), but subsequent surgery on either knee within one year was much more common (a 6.5% rate). Patients were at increased risk for readmission within ninety days if they were over forty years of age, sicker (e.g., had a preexisting comorbidity), male, and operated on by a lower-volume surgeon. Predictors of subsequent knee surgery included being female, having concomitant knee surgery, and being operated on by a lower-volume surgeon. Predictors of a subsequent anterior cruciate ligament reconstruction included an age of less than forty years, concomitant meniscectomy or other knee surgery, and surgery in a lower-volume hospital. The rate of anterior cruciate ligament reconstruction has increased in frequency. Also, while anterior cruciate ligament reconstruction appears to be a safe procedure, the risk of a subsequent operation on either knee is increased among younger patients and those treated by a lower-volume surgeon or at a lower-volume hospital.

To determine the prophylactic capability of anterior cruciate ligament (ACL) reconstruction in decreasing the risk of knee osteoarthritis (OA) when compared with ACL-deficient patients, as well as the effect of a concomitant meniscectomy. We also sought to examine the influence of study design, publication date, and graft type as well as the magnitude of change in physical activity from preinjury Tegner scores in both cohorts.